1. Field of the Invention
This invention relates to elastomeric foam formed from aqueous silicone emulsion which contains inorganic fibers.
2. Background Information
Mueller et al. in U.S. Pat. No. 3,311,115, issued March 28, 1967, describe an isotropic, porous cellular foamed fibrous structure, useful in the filtration of aerosol suspensions; i.e., a cigarette filter. Their structure is formed by preparing a slurry of fibrillated cellulosic fibers, then treating them with wet strength resin and compatible latex binder. The slurry is then foamed and cast into desired filter shapes and dried to result in the breaking of the foam, leaving fibers bound together with from about 1 to 20 percent by weight of coagulated latex in an isotropic, cellular fibrous structure.
Modic, in U.S. Pat. No. 3,425,967, issued Feb. 4, 1969, teaches a foamable organopolysiloxane composition and the flexible foams produced from the compositions. His foams contain a vinyl chain-stopped diorganopolysiloxane, a vinyl containing resinous copolymer, a liquid organohydrogenpolysiloxane, and a platinum catalyst to form a curable silicone elastomer. The composition also contains a blowing agent to form the foam, an inorganic fibrous material selected from the class consisting of asbestos and fibrous potassium titanate, and optionally, a finely divided inorganic filler. The inorganic fibrous material is stated to result in a foamed product having increased strength and unexpectedly adds strength to the product resulting from the severe burning of the cured silicone foam. The compositions are converted to foam by heating the entire mixture of ingredients to an elevated temperature, such as 80.degree. to 180.degree. C.
Modic, in U.S. Pat. No. 4,189,545, issued Feb. 19, 1980, teaches a silicone foam comprising a vinyl-containing polysiloxane, optionally a filler, water, a hydrogen-containing polysiloxane, and a platinum catalyst. The ingredients react upon mixing to liberate hydrogen and form a foam which cures to a silicone elastomeric foam. Among the optional fillers suggested is glass fibers along with other extending filler such as carbon, calcium carbonate, and ground quartz.
Sands, in U.S. Pat. No. 4,473,667, issued Sept. 25, 1984, discloses a method of producing a silicone elastomeric foam from an aqueous silicone emulsion suitable to provide an elastomeric product upon removal of the water. He mechanically generates a stable froth, then removes the water to form cured elastomeric foam. He stabilizes the froth with the proper use of surfactant and thickener.